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Quantitative 3D magnetic resonance elastography: Comparison with dynamic mechanical analysis

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ABSTRACT

Purpose: Magnetic resonance elastography (MRE) is a rapidly growing noninvasive imaging technique for measuring tissue mechanical properties in vivo. Previous studies have compared two‐dimensional MRE measurements with material properties from dynamic mechanical analysis (DMA) devices that were limited in frequency range. Advanced DMA technology now allows broad frequency range testing, and three‐dimensional (3D) MRE is increasingly common. The purpose of this study was to compare 3D MRE stiffness measurements with those of DMA over a wide range of frequencies and shear stiffnesses.

Methods: 3D MRE and DMA were performed on eight different polyvinyl chloride samples over 20–205 Hz with stiffness between 3 and 23 kPa. Driving frequencies were chosen to create 1.1, 2.2, 3.3, 4.4, 5.5, and 6.6 effective wavelengths across the diameter of the cylindrical phantoms. Wave images were analyzed using direct inversion and local frequency estimation algorithm with the curl operator and compared with DMA measurements at each corresponding frequency. Samples with sufficient spatial resolution and with an octahedral shear strain signal‐to‐noise ratio > 3 were compared.

Results: Consistency between the two techniques was measured with the intraclass correlation coefficient (ICC) and was excellent with an overall ICC of 0.99.

Conclusions: 3D MRE and DMA showed excellent consistency over a wide range of frequencies and stiffnesses. Magn Reson Med 77:1184–1192, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

No MeSH data available.


Representative example of a PVC 95‐05 sample. Top row: Effective wavelength n across the phantom diameter. Second row: Corresponding driving frequencies. Third row: X‐component of the curled wave images of the center slice. Fourth row: Number of pixels per wavelength (p/λ). Fifth row: Color scale for the MRE DI magnitude of complex shear modulus in kPa. Sixth row: Elastograms from DI. Seventh row: Elastograms with pixels having OSS‐SNR > 3 used to calculate the mean MRE DI magnitude of complex shear modulus.
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mrm26207-fig-0003: Representative example of a PVC 95‐05 sample. Top row: Effective wavelength n across the phantom diameter. Second row: Corresponding driving frequencies. Third row: X‐component of the curled wave images of the center slice. Fourth row: Number of pixels per wavelength (p/λ). Fifth row: Color scale for the MRE DI magnitude of complex shear modulus in kPa. Sixth row: Elastograms from DI. Seventh row: Elastograms with pixels having OSS‐SNR > 3 used to calculate the mean MRE DI magnitude of complex shear modulus.

Mentions: DMA results showed that the eight PVC samples had stiffnesses in the range of 3−23 kPa. The average standard error across all the PVC samples based on the 10 measurements for each frequency was 4.75%. Supporting Tables S1–S8 show the effective wavelength (λeff); corresponding number of pixels per wavelength; driving frequency for each effective wavelength; magnitude of the complex modulus, storage modulus, and loss modulus for DMA and MRE DI; LFE shear stiffness; average OSS‐SNR values; and the percentage of pixels with OSS‐SNR >3 in the included volume for each PVC sample. Supporting Tables S1–S8 correspond to PVC 50‐50, PVC 60‐40, and so forth up to PVC 95‐05, respectively. Figure 3 shows a representative example of the X‐component of the curled data, the corresponding elastograms, and a map of the voxels with OSS‐SNR > 3 for wavelengths 1.1, 2.2, 3.3, 4.4, 5.5, and 6.6 for PVC 95‐05. DMA testing revealed that this sample had a magnitude of complex shear modulus between 3 and 23 kPa for the frequency range 10–250 Hz. Figure 4 shows the X‐component of the curled data for 4.4 effective wavelengths for all eight PVC samples with their associated frequencies of vibration.


Quantitative 3D magnetic resonance elastography: Comparison with dynamic mechanical analysis
Representative example of a PVC 95‐05 sample. Top row: Effective wavelength n across the phantom diameter. Second row: Corresponding driving frequencies. Third row: X‐component of the curled wave images of the center slice. Fourth row: Number of pixels per wavelength (p/λ). Fifth row: Color scale for the MRE DI magnitude of complex shear modulus in kPa. Sixth row: Elastograms from DI. Seventh row: Elastograms with pixels having OSS‐SNR > 3 used to calculate the mean MRE DI magnitude of complex shear modulus.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036985&req=5

mrm26207-fig-0003: Representative example of a PVC 95‐05 sample. Top row: Effective wavelength n across the phantom diameter. Second row: Corresponding driving frequencies. Third row: X‐component of the curled wave images of the center slice. Fourth row: Number of pixels per wavelength (p/λ). Fifth row: Color scale for the MRE DI magnitude of complex shear modulus in kPa. Sixth row: Elastograms from DI. Seventh row: Elastograms with pixels having OSS‐SNR > 3 used to calculate the mean MRE DI magnitude of complex shear modulus.
Mentions: DMA results showed that the eight PVC samples had stiffnesses in the range of 3−23 kPa. The average standard error across all the PVC samples based on the 10 measurements for each frequency was 4.75%. Supporting Tables S1–S8 show the effective wavelength (λeff); corresponding number of pixels per wavelength; driving frequency for each effective wavelength; magnitude of the complex modulus, storage modulus, and loss modulus for DMA and MRE DI; LFE shear stiffness; average OSS‐SNR values; and the percentage of pixels with OSS‐SNR >3 in the included volume for each PVC sample. Supporting Tables S1–S8 correspond to PVC 50‐50, PVC 60‐40, and so forth up to PVC 95‐05, respectively. Figure 3 shows a representative example of the X‐component of the curled data, the corresponding elastograms, and a map of the voxels with OSS‐SNR > 3 for wavelengths 1.1, 2.2, 3.3, 4.4, 5.5, and 6.6 for PVC 95‐05. DMA testing revealed that this sample had a magnitude of complex shear modulus between 3 and 23 kPa for the frequency range 10–250 Hz. Figure 4 shows the X‐component of the curled data for 4.4 effective wavelengths for all eight PVC samples with their associated frequencies of vibration.

View Article: PubMed Central - PubMed

ABSTRACT

Purpose: Magnetic resonance elastography (MRE) is a rapidly growing noninvasive imaging technique for measuring tissue mechanical properties in vivo. Previous studies have compared two‐dimensional MRE measurements with material properties from dynamic mechanical analysis (DMA) devices that were limited in frequency range. Advanced DMA technology now allows broad frequency range testing, and three‐dimensional (3D) MRE is increasingly common. The purpose of this study was to compare 3D MRE stiffness measurements with those of DMA over a wide range of frequencies and shear stiffnesses.

Methods: 3D MRE and DMA were performed on eight different polyvinyl chloride samples over 20–205 Hz with stiffness between 3 and 23 kPa. Driving frequencies were chosen to create 1.1, 2.2, 3.3, 4.4, 5.5, and 6.6 effective wavelengths across the diameter of the cylindrical phantoms. Wave images were analyzed using direct inversion and local frequency estimation algorithm with the curl operator and compared with DMA measurements at each corresponding frequency. Samples with sufficient spatial resolution and with an octahedral shear strain signal‐to‐noise ratio > 3 were compared.

Results: Consistency between the two techniques was measured with the intraclass correlation coefficient (ICC) and was excellent with an overall ICC of 0.99.

Conclusions: 3D MRE and DMA showed excellent consistency over a wide range of frequencies and stiffnesses. Magn Reson Med 77:1184–1192, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

No MeSH data available.